This invention relates to a wedging clamp device for insertion between two parts, capable of performing a relative movement in relation to one another, in order to prevent their relative movement. The device is particularly useful in order to prevent relative movement between a brake disk and a brake caliper of a vehicle brake, comprising two plates, the separation between which is adjustable by means of at least two opposed rollers rolling on rolling surfaces on opposing inner sides of the plates. For bringing about wedging in an extended state, the separation of the plate is greater when the rollers are situated in the area of a first section of the rolling surfaces than the separation, assumed by the plates for release of wedging in a retracted state, when the rollers are situated in the area of a second section of the rolling surfaces. The position of the rollers relative to the rolling surfaces is adjustable by means of an actuating device.
Such a wedging clamp device is disclosed by U.S. Pat. No. 4,121,696. A disadvantage with this wedging clamp device, however, is that the normal force needed to generate wedging friction is produced by a displacement of rollers along the rolling surfaces, so that in order to generate greater holding forces, as are necessary for vehicle parking brakes, for example, the actuating device must exert correspondingly large actuating forces, which makes the device bulky and expensive. A relatively large energy input is then needed for the actuating device. Finally, the rollers have a tendency to wear, owing to the movement occurring under large forces.
One object of the present invention is to create a wedging clamp device which largely eliminates these disadvantages.
According to the invention, this object is achieved by having at least two wedges that can be wedged against one another, with at least one of the wedges being actuatable by a further actuating device in the wedging or release direction. One actuating device first brings the plates from their retracted position into the extended state, and the further actuating device then actuates at least one of the wedges, in a direction preventing a relative movement between the two parts, in order to bring about wedging. The one actuating device brings the plates from their extended position into the retracted position, and the further actuating device actuates at least one of the wedges in a direction allowing a relative movement between the two parts in order to release the wedging.
Compared to known devices, this has the advantage that the normal force required to generate the wedging friction between the two parts moving relative to one another is produced by actuation of at least one of the wedges instead of by actuation of the rollers. Due to friction, this wedge is then carried by the still moving part, or the part still subject to a torque or force, such as a brake disk, and wedges further against the other wedge, resulting in a greater thickness of the wedge assembly, an increase in the normal force, and, ultimately therefore, also an increase in the friction forces, so that the moving part or the part still under torque or force is finally frictionally locked to the other part. The rollers, on the other hand, are not actuated during the wedging process. They are in a position in which the plates are extended.
The plates of the wedging clamp device may separate and come together in a substantially linear and parallel manner due to the movement of the rollers along the rolling surfaces. Alternatively the wedging clamp device may act like a folding wedge, in that the plates fold out and in at an angle to one another.
In one preferred embodiment, the plates can be folded out and in at an angle to one another under a rotational movement about an articulated connection arranged at their ends. The other ends are provided with the rolling surfaces. This gives the wedging clamp device a wedge-shaped cross section in the extended or deployed state so that it will wedge between the parts performing the relative movement in relation to one another, preferably until self-locking occurs.
According to another measure, the actuating device has a spring, which preloads the plates into the extended position. In order to achieve a defined rolling behavior on the rolling surfaces, the rollers, viewed in an axial direction, may each have, at least in sections, a circumferential external toothing, which meshes with toothing systems on the rolling surfaces. An advantageous dual function of the toothing is obtained, namely defined guiding of the rollers against the plates and an actuating drive, if the actuating device comprises a rack arranged between the rollers, which rack has a double toothing on the longitudinal sides remote from one another and which meshes with the external toothing systems of the rollers. The rollers can then be guided along the rolling surface by the linear motion of the rack, for which purpose a simple linear drive, even a manual one, for example, will suffice. The toothing systems give the rollers a defined rolling behavior, thereby also achieving a defined wedging and release behavior.
If the spring serves to preload the rack into a position in which the rollers are situated in the area of the first section of the rolling surfaces, the wedging clamp device will always be automatically preloaded into its deployed position without the need for further measures or manual operations. The wedging action can then easily be released by a linear movement of the rack against the action of the spring, causing the rollers to roll into the area of the second section of the rolling surfaces, whereupon the wedging clamp device shifts into the retracted position. This will allow wedging and release of the wedging clamp device to be repeated any number of times.
According to certain features, multiple rolling surfaces and rollers can also be arranged in series, which allows very large wedging forces to be generated.
One embodiment provides for a parallel connection of the two plates, adjustably separated by the rollers.
The invention further provides for a vehicle brake device, particularly for a commercial vehicle, comprising a disk brake with a brake disk and a brake caliper which is designed for the insertion of a wedging clamp device according to the invention. In this device a wedge face of the brake caliper is most preferably formed with a wedge angle in relation to the plane of the brake disk, in such a way that with the brake disk rotating in relation to the brake caliper, and the wedging clamp device inserted in an extended or deployed state between the wedge face of the brake caliper and the brake disk, the wedging clamp device wedges ever more tightly until self-locking occurs. Consequently the spring mainly serves to preload the wedging clamp device into the deployed position and in an ancillary manner for generating the normal forces from which the friction force of the brake disk ensues. The spring can therefore be designed smaller and lighter, and the actuating forces are low, so that the wedging clamp device is easy to operate manually and a small, lightweight drive is sufficient for the rack.
The outer face of one plate is most preferably intended to bear against the brake disk of the vehicle brake and has a higher coefficient of friction than the outer face of the other plate, which is intended to bear against a wedge face of the brake caliper of the vehicle brake opposite the brake disk and is therefore likewise of wedge-shaped design. The higher coefficient of friction on the one plate can be accomplished, for example, by a separate friction lining, which ensures that static friction between the brake disk and the wedging clamp device is achieved. The outer face of the other plate, on the other hand, need not have a high coefficient of friction, since it is secured to the wedge face of the brake caliper by positive interlock and thereby generates the normal force necessary for the static friction.
The construction of the wedging clamp device according to the invention will be apparent from the following description.
Exemplary embodiments of the invention are represented in the drawings and are explained in more detail in the following description.